1. Field of the Invention
The invention relates to a quick adjusting nut made especially for attaching a vehicle wheel to the mounting shaft of a balancing machine, with a housing part and with at least two thread segments that are radially movably arranged in the housing part, and with an actuating means for radially moving the thread segments, each thread segment having an inside thread section and the thread segments being movable along guide surfaces of the housing part from an engagement position in a radially outward direction into a disengagement position.
2. Description of Related Art
A quick adjusting nut of the aforementioned type is known from German Application DE 36 05 821 A1 and corresponding U.S. Pat. No. 4,768,909. The known quick adjusting nut has a housing on which there are two handles for tightening the quick adjusting nut. Slots with lateral guide surfaces and axial guide surfaces are arranged in the housing diametrically opposite each other. In each slot is a segment which has an inside thread, supported to be able to move radially, an axial face surface of the segment interacting with an axial face surface of the slot. Upper axial face surfaces of the segments adjoin a disk which is supported in a face-side recess so as to be able to turn with little play, its being held from the outside by a housing cover which is attached to the housing by means of screws. In the region of their upper axial face surfaces, the segments have short pins which engage inclined slots in the disk, and thus, together with the latter form a connecting link guide. Between the disk and the housing cover is a helical spring which has a respective end connected to the disk and the housing cover and is pretensioned such that the disk is pretensioned clockwise, as a result of which, at the same time, the segments are pressed radially to the inside via the connecting link guide. On the disk are arms for actuating the disk in the direction of rotation against the force of the helical spring.
When the known quick adjusting nut is being used in conjunction with a balancing machine to balance vehicle wheels, first a vehicle wheel with its rim is slipped onto the shaft of the balancing machine, this shaft having an outside thread according to the inside thread of the quick adjusting nut. Afterwards, the quick adjusting nut is grasped with one hand, for example, on the handle, pressing with the thumbs against one arm of the disk, and thus, the disk being pressed counterclockwise against the force of the helical spring. The segments are moved radially to the outside into a disengagement position by the connecting link guide. In this state, the quick adjusting nut can be pushed beyond the thread of the axle of the balancing machine and pressed against the rim which, on the side which faces away, comes into contact with a corresponding flange. If the quick adjusting nut has been sufficiently pressed, the thumb is removed from the arm so that the helical spring moves the disk counterclockwise. In this way, the segments are moved radially to the inside via the connecting link guide so that the inside thread sections of the segments fully engage the outside thread of the axle of the balancing machine. Due to the power transmission in the connecting link guide, the thread segments are locked at the same time in the closed position since under these conditions the connecting link guide is self-locking. Finally the quick adjusting nut is tightened by means of the two handles.
Moreover German Application DE 36 05 821 A1 and corresponding U.S. Pat. No. 4,768,909 disclose another quick adjusting nut which in the radial direction has thread segments which can be pivoted to the outside and which are coupled via a connecting link guide to a disk, wherein the use of the quick adjusting nuts takes place in the same way as indicated above. Here, the thread segments will not be able to move apart automatically due to the self-locking of the indicated connecting link guide so that the quick adjusting nut is locked in the clamped position.
In the known quick adjusting nuts, when the inside thread sections of the thread segments are compressively loaded, force components arise which act, for example, on the thread segments and which are directed via the outside thread, for example, of the shaft of a balancing machine in the radial direction to the outside. These opening forces which are directed to the outside are to be captured by the control disk which is connected to the thread segments via the connecting link guide in the known quick adjusting nuts. However, the connecting link guide is subject to play due to production tolerances. The existing play especially with increasing thread wear can lead to the thread segments under compressive loading being pressed away from one another in the radial direction due to the force components which arise and being moved into a disengagement position. Moreover, the thread sections of the thread segments for the known quick adjusting nuts are subject to increased wear; this increases the danger of self-opening of the thread under compressive load. Finally the known quick adjusting nuts have a comparatively large overall height; this is likewise disadvantageous.